Oh, boy
by Dellinah
Summary: It was weird enough that Mabel didn't know what a period was when she was 14. But it was even more awkward when Stan was the one who had to help her through her first one - and make sure he didn't freak out as well. Mabel & Stan bonding one-shot.


**I hadn't written anything for Gravity Falls in a while now, and this is the first one I wrote that isn't focused on Stan and Ford. I had this idea earlier today and thought it'd be a cute Stan/Mabel story.**

 **Rated T just to be safe.**

* * *

Stan sat in his usual spot, right outside the Mystery Shack. He blew his coffee to cool it down a little, watching as the fog that went up from it disappeared into the cold morning breeze. With a relaxed sigh, he leaned back, placing his other hand behind his head and admiring the view he had in front of him.

It was almost too hard for him to believe that one year before, in that same day, that town was being taken over by a triangle demon who almost killed everyone. Which had happened after his brother came back from another dimension. Which had happened after Stan lied about everything to everybody to be able to work on a portal.

Well, what could he say? Trouble was his middle name.

Looking back at it, he almost felt like his current routine was boring in comparison to what he had to do just a year before. But he wouldn't trade it for the world.

Soos, his grandmother and his bride to-be had gone off to visit Soos' cousin for the summer, so he let Stan and Ford stay in the Shack once more. And of course, Mabel and Dipper had come back to visit their grunkles.

It took them three days to tell the kids all about the adventures they had had while sailing on the sea for that past year. Stan and Ford knew that nobody but those kids would believe what they had to tell – monsters, aliens, paranormal events… If they told those to anyone else, they'd send the two men to the asylum in a heartbeat.

It had only been a year, but Stan felt like the kids had changed so much. They were taller now; with Mabel becoming more of a teenager and less of a kid and with Dipper beginning to sprout a few, but nonetheless impressive, hairs on his face. Stan joked saying that maybe three years from there he'd have grown enough hair to look like he had a shaved bear, but Dipper knew that he was proud on the inside. And he really was.

Barely a week after the kids had arrived, Dipper and Ford had already begun to work on their projects together, something they had been planning to do since the previous summer. Mabel had thought their grunckles to use this weird program on their phones – Skype? Something like that – and Dipper would use his camera phone to show weird things he found to Ford and ask his opinions about what they were. Sometimes he went a little overboard, like the time he thought a weird triangle rock was the tip of an arrow of an ancient civilization; but that boy had really taken after Ford.

They had left early that morning, with Stan barely having time to say goodbye when he woke up to find the duo already with their backpacks on their backs as they left to the wild, to investigate something weird. That's all Stan knew, and to be honest, he didn't want to know any more about what those two found out in Gravity Falls. They may be enthusiastic, but Stan had had his fair share of anomalies for this lifetime. And three more.

The mug of coffee was no longer too warm to hold, meaning that Stan could finally drink it now. However, just as he took the cup to his lips to take the first sip, a high-pitched scream filled the air, startling him so much that he lost his balance and fell forward on the ground; his mug flying ahead him before it fell and broke, coffee spilling around it.

However, Stan didn't care for that. He jumped up and entered the Shack, running faster than ever before. The scream he heard was a familiar one – it belonged to Mabel, and it came from her room. The girl had stood up late the night before in a movie marathon with her friends, so Stan thought he might as well let her sleep in. But without a doubt, she was awoken now.

Stan burst through the door of the two-bed room, cursing threats and holding a baseball bat and waving it around, ready to fight anyone (or anything demonic) who had startled his niece. But he dropped it to his side when he saw that there was nothing there for him to fight; just Mabel. She was alone in the room, sitting on her bed and hugging her knees while she sobbed.

"Mabel, what's wrong?" Stan dropped the bat to the floor and ran to her side, running his hand through her hair and tucking a loose strand behind her ear to keep it away from her eyes, "Are you sick? Did you have a nightmare? I heard you scream!" He pleaded when she didn't say anything.

Mabel raised her head from her knees, looking up at Stan with water-filled eyes and a quivering lip. She was also sweating a lot, with some strands of hair falling wet over her face.

"Darling, what's wrong?" Stan asked again, voice soft, as he wiped her eyes and sweaty forehead. He was now convinced that Mabel was sick or had had a nightmare and there was no danger, thankfully. But if that was the case, her scream had been really exaggerated.

Instead of answering, Mabel bit her lower lip and shyly reached for the blanket of the bed, lifting it and unfolding her legs. It all became clear to Stan when he saw the red stain on the sheets and over Mabel's pants. He didn't know whether to be relieved or even more worried at the sight.

"Grunkle Stan, I, I woke up covered in blood today," She muttered, voice quivering, "Am I dying?"

Stan's eyes widened. He half expected her to begin laughing and say she was pulling a prank on him, but he knew that she was being completely serious about that question. She was going to be 15 in a few weeks and she still didn't know what a period was? Her parents should really begin to talk to her more.

"Mabel, sweetie, you're not dying," Stan cooed, hoping that his sweet tones would calm Mabel down, "You just got your first period, that's all."

The answer seemed to have confused Mabel even more as she raised an eyebrow at Stan. "My what?"

 _Oh, boy_. Stan thought to himself. How was he supposed to handle that? He didn't know how to have that talk with her. It felt wrong, weird even. But he couldn't just turn his back and leave Mabel there, clueless about her own body.

Stan took the dirty blanket away and folded it, signing for Mabel to stand up. She was reluctant for a while, but finally did so, folding one of her knees so that it covered most of her crotch.

"Listen here, kiddo," Stan Said as he took the dirty sheet away as well, "You go take a warm, nice shower and clean yourself. You're alright. I'll go to the town really quick, and when I'm back we'll have a talk, ok?"

"F-Fine," She sputtered in a whisper, going to the bathroom. She closed the door and opened it a crack a few moments later, throwing out her dirty clothes which Stan grabbed as well and went to the laundry, where he put everything in the washing machine. He went upstairs again just to make sure Mabel was alright before he ran to his car and drove into town, hoping God would help him.

* * *

God seemed to have heard Stan's prayers as the salesperson who helped him at the store was a young girl who looked just above eighteen. After a quick – and awkward talk – he had with her to explain what had happened, she helped him buy what he needed. Stan wondered if other men had done that before, as she seemed very familiar with the "help a stranger find women's products they had never needed before and knew nothing about" situation. He smiled at her and waved goodbye when she wished him good luck.

The idea of paying her to go home and explain all that to Mabel instead went through Stan's head. He had to admit it seemed very tempting.

He drove home as quickly as he had left, running upstairs. The bedroom was closed, and he almost opened it and entered the room; but decided to knock first, given the circumstances. After a few seconds, a weak voice came from the room telling him to go in.

Mabel sat on her bed, wearing nothing a towel wrapped around her body as she braced herself. Her hair was wet and strings of water ran down her back, soaking the towel. She sniffed as Stan went in and sat by her side.

"I didn't know if I should get dressed," Mabel uttered, "I, I was afraid I'd get them dirty again."

"Hey, Mabel, it's okay. You're just fine."

She gave Stan a doubtful look, the same look his mother gave him when he lied about who had eaten the last cookie in the jar before dinner.

"Listen, kiddo," He took a deep breath and pinched the bridge of his nose, "Hum, once a month women, well, you see… Women produce an egg every month, and-"

"You mean I'll lay an egg?!" She yelled, eyes wide.

"No, no, no!" Stan held out his hands, "Not like, an egg, egg. Hum, well, you know that women are the ones who carry the babies, right?"

She nodded.

"Okay, so, hum, let's see… The baby comes from an 'egg' that the woman produces," He said, with finger quotes to make sure she wouldn't freak out again, "Women produce an egg every month. When the egg is fertilized, it grows into a baby. But when the egg doesn't become a baby, the body must get rid of it, so you bleed it. Sort of. That's what a period is, when you bleed through your- uh, when you bleed every month, because you're not pregnant."

Mabel shuddered.

"What do I do now, then?" She asked him, fear in her big eyes.

"Hum, oh yeah, you just got to wear these." He handed her the plastic bag he brought with him from the market. "There, there are instructions on the package. You wear these, they keep the blood in, then you throw it away. Uh, and put on a new one if your period isn't over yet."

She frowned and looked at the package in her hands as if she was looking at one of Ford's inventions.

"Here," He handed her some clean clothes he grabbed for her in the laundry after putting them in the dryer so that they'd be warm for her. "Go to the bathroom and just try to put it on. You can call me if you need help."

Stan smiled at her, trying to comfort her. Mabel just nodded and sighed, still looking as confused as before when she stood up from the bed and went to the bathroom again, leaving a trail of water that ran down from her hair as she walked.

Stan then took the mattress off the bed, as it also had been stained with blood; and folded it in the corner of the room so that he could wash it later as well. He waited what seemed to be an eternity for Mabel to come out of the bathroom. When she opened the door again she stood still with the open package of pads in her hands, looking a little bit more relieved than when she went in the bathroom.

"Are you okay?" Stan asked as she walked toward him, and she nodded. Her cheeks were red and she had her hands behind her back, and Stan knew she was embarrassed. He pulled her into a hug and she hugged back, her heartbeat slowing.

"What about we go to the kitchen and have a nice breakfast?"

Mabel looked up at him, her frown slowly becoming a smile as she nodded.

* * *

"So, once a month I'll bleed through, uh, there, and that means I'm not pregnant?"

"Yes, that's about it." Stan replied, sitting across from Mabel on the table. She seemed distressed and had barely eaten anything from her cereal bowl, but began eating more after every question her Grunkle answered.

"Ugh. How long does it last?" She whined, shifting her legs in discomfort at the thought.

"Uh, it depends, I think," Stan did his best to remember what it was like with his mother and the girlfriends he had had, but he never asked them in details about it. "I think five days? Something like that. Your mom will be able to give you an answer. Want to call her?"

Mabel shook her head. "Nah… I can wait." She took a sip of her chocolate milk, "Uh, how often do I have to change the, hum, the thing?"

Stan took another deep breath.

"I, I can't give you a specific answer," He stuttered, feeling his face getting read. It felt too weird to discuss that with Mabel. He still saw her as a little kid. "I'd say, whenever the one you're with gets dirty."

Mabel buried her face in her hands. "This is disgusting."

"Hey, no it's not, it's nature," Stan comforted her, reaching for her hand on the table and taking it in his, "Nothing to be ashamed or disgusted of. Just, every woman goes through that. You'll learn to deal with it as you get older."

Mabel squeezed Stan's hand. "Thanks, Grunkle Stan. I don't know what I'd do without you. Think we can keep it a secret till summer ends? I don't want anyone to know about it until I know it better."

He laughed and pretended to zip his mouth shut. "No prob. And if you run out of pads, just tell me and we'll go get more."

Mabel blushed lightly, looking down and never letting go of Stan's hand. For the first time, he saw her as a woman, and not the little girl with braces who had spent summer with him. Still, her confusion and curiosity about it were like those of a little girl. Stan nodded and squeezed her hand to reassure her one more time before he stood up to take the dishes to the sink. He felt embarrassed, but he could only imagine how embarrassed she was; so, he had to be as natural as possible to calm her down. One of them being confused was bad enough.

"Hey, Grunkle Stan?" She called from the table as he washed the dishes.

"Yes, dear?"

"How does the, uh, egg get turned into a baby?"

He loosened the grip on the mug he was washing and almost let it fall as he turned to her with wide eyes.

"Sorry, but _that_ you'll have to ask your mom when summer ends."

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 **Thanks for reading, I hope you enjoyed! Let me know your thoughts. See yah next fic!**


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